This mount has the muscle to handle even the largest (15″ & 16″) sonar units on the market. Pre-drilled and tapped to accept an array of sonar accessories and can be used with our Over & Under (Stack) Mount for or Large Gimbal Bar for those who want dual mounts at the bow of their earlier model boats. Add a pair of our SmartBrackets to form a Commercial Grade Bow Mount and the ultimate in reliability and protection. Measures 21″ L x 4 1/2″ W with a Bridge Measurement of 16 5/8″